The long term objective of this proposal is to gain insights into the neuron generation potential of the mammalian retinal-ciliary margin as well as the molecular and cellular properties of cells within. This has important implications for the regeneration of functional neurons in damaged retinas. The proposal focuses on the retinal ganglion cell (RGC) forming competency of cells at the retinal-ciliary margin. RGCs play an essential role in visual function. Abnormalities in RGCs lead to major eye diseases in humans including glaucoma, Norrie disease, and other optic neuropathies. Stem cell administration, including supplementary of healthy retinal stem cells and in vivo activation of potential retinal stem cells, raises the hope for treating these diseases. However, isolated adult stem cells from the ciliary margin have limited differentiation potential;they do not give rise to RGCs and other "early" retinal cell types. The molecular and cellular mechanism negatively regulating RGC formation at the mammalian retinal-ciliary margin remains largely unknown. Recent advances in mouse genetic engineering and gene delivery technologies have provided new tools for exploring properties of the retinal-ciliary margin. This application will explore the molecular and cellular properties of the retinal-ciliary margin. Based on the hypothesis that cells in the retinal margin can retain their RGC forming competency for a latent period of time but eventually lose such a potential, three specific aims are proposed: 1) Determine how long can the mammalian retinal-ciliary margin retain its potential of forming new neurons. 2) Determine whether RGCs can be produced if new neuron is generated. 3) Determine whether RGCs, the first born retinal cell type, can be produced from the adult ciliary margin when minimal cell-intrinsic factors are supplied. Proposed experiments will take advantage of the advanced conditional gene targeting strategy and genetic engineered mouse lines generated during our past studies in quest of molecular mechanism in RGC formation. Results of these experiments will allow us to determine the state of competency of the ciliary margin cells at any given time. The results will also shed light into the regulation mechanism at mammalian retinal margin and provide information for designing treatments to cell degeneration related retinal diseases. PUBLIC HEALTH RELEVANCE: The proposed project studies cellular and molecular properties in the mammalian retinal margin. The result of this study will provide valuable information on utilizing cells from the retinal margin to replenish diseased or damaged retina.